Merge pull request #1175 from karlnapf/develop

added get_width and obtain_from_generic for Chi2 kernel

src/shogun/kernel/Chi2Kernel.cpp

@@ -80,3 +80,21 @@ float64_t CChi2Kernel::compute(int32_t idx_a, int32_t idx_b)
 
 	return result;
 }
+
+float64_t CChi2Kernel::get_width()
+{
+	return width;
+}
+
+CChi2Kernel* CChi2Kernel::obtain_from_generic(CKernel* kernel)
+{
+	if (kernel->get_kernel_type()!=K_CHI2)
+	{
+		SG_SERROR("Provided kernel is "
+				"not of type CChi2Kernel!\n");
+	}
+
+	/* since an additional reference is returned */
+	SG_REF(kernel);
+	return (CChi2Kernel*)kernel;
+}

src/shogun/kernel/Chi2Kernel.h

@@ -64,6 +64,15 @@ class CChi2Kernel: public CDotKernel
 		 */
 		virtual bool init(CFeatures* l, CFeatures* r);
 
+		/** @return width of the kernel */
+		virtual float64_t get_width();
+
+		/** @param kernel is casted to CChi2Kernel, error if not possible
+		 * is SG_REF'ed
+		 * @return casted CGaussianKernel object
+		 */
+		static CChi2Kernel* obtain_from_generic(CKernel* kernel);
+
 		/** return what type of kernel we are
 		 *
 		 * @return kernel type CHI2